Fix incorrect error message capitalization

Author: deivid-rodriguez

bundler/lib/bundler/definition.rb

@@ -533,7 +533,7 @@ def lockfile_changes_summary(update_refused_reason)
 
       return unless added.any? || deleted.any? || changed.any? || resolve_needed?
 
-      msg = String.new("#{change_reason.capitalize.strip}, but ")
+      msg = String.new("#{change_reason[0].upcase}#{change_reason[1..-1].strip}, but ")
       msg << "the lockfile " unless msg.start_with?("Your lockfile")
       msg << "can't be updated because #{update_refused_reason}"
       msg << "\n\nYou have added to the Gemfile:\n" << added.join("\n") if added.any?

bundler/spec/commands/update_spec.rb

@@ -1809,7 +1809,7 @@
     system_gems "bundler-9.9.9", path: local_gem_path
 
     bundle "update --bundler=9.9.9", env: { "BUNDLE_FROZEN" => "true" }, raise_on_error: false
-    expect(err).to include("An update to the version of bundler itself was requested, but the lockfile can't be updated because frozen mode is set")
+    expect(err).to include("An update to the version of Bundler itself was requested, but the lockfile can't be updated because frozen mode is set")
   end
 end
 

bundler/spec/lock/lockfile_spec.rb

@@ -1638,7 +1638,7 @@
     G
 
     expect(err).to eq <<~L.strip
-      Your lockfile is missing a checksums entry for \"myrack_middleware\", but can't be updated because frozen mode is set
+      Your lockfile is missing a CHECKSUMS entry for \"myrack_middleware\", but can't be updated because frozen mode is set
 
       Run `bundle install` elsewhere and add the updated Gemfile.lock to version control.
     L